Aeroplane guiding light



March 27, 1928. 1,664,170

' w. F. HENDRY AEROPLANE GUIDING LIGHT Filed April 28. 1927 In mentorAttorney Patented Mar. 27,1928.

UNITED STATES 1, 64,170 PATENT OFFICE.

WILLIAM F. HENDRY, OF OSSININ'G, YORK, ASSIGNOR TO MANHATTAN ELECTRI-CAL SUPPLY COMPANY, INC., A CORPORATION'OF MASSACHUSETTS.

' AEROPLANE GUIDING LIGHT.

Application filed April 28; 1927. Serial No. 187,295.

This invention relates to light beacons and relates more particularly toelectric light beacon systems for guiding aeroplanes.

An object of my invention is the provision of an aeroplane light beaconhaving a distinguishing characteristic which can readily of the lightemitted by the beacon.

, providing a light source which is periodi More specificallymy'invention consists in cally extinguished and in providing on theaeroplane means for detecting the frequency of the light fluctuations.-The light source preferably consistsof a gas discharge tube of the typecomprising a transparent or translucent envelope enclosing twoelectrodes and a filling of rare gas such as neon or helium, under lowpreure. For best results the tube should be of the rectifying type such,for example, as a tube containing electrodes of unequal. size, but maybe of any well-known type. The means for detecting the frequency of thelight source preferably comprises the propeller of the aeroplane and atachometer for registering the speed of the propeller.

An aviator using the system would view the beacon light through theaeroplane propeller and then throttle the engine until the propellerappeared to stand stationary, at .which time the propeller would berotating at a speed in synchronism with the light frequency, or somewhole multiple of that frequency. When an ordinary lighttube and sourceof energy is used the frequency of the light fluctuations can bedetermined but the propeller doe; .1013 appear so clear cut as when arectifying light tube is used. When the latter type of tube is used, thepropeller stands out much more clearly, due, probably, to the fact thatthe light is entirely out half of the time, rather than entirely outonly a very short portion of the time. 'The same effect obtained byusing a rectifying tube could also be secured by using an ordi-. narylight tube and rectifying the alternating supply current in such mannerthat a] half wave only would be supplied to the tube.

I have suggested the use of gas discharge light tubes as it is wellknown that when such tubes are used on a. circuit of varying voltage.the light produced by the tube varies with the impressed voltage, evenwhen the voltage fluctuates at a' very high frequency. However, anyother well-known source of light having the same charactertistics mightbe used as well.

The invention with its further objects and advantages will be more fullyexplained by the following description 'taken in conjunc tion with theaccompanying drawings.

In Fig. 1, Which represents a beacon light system according to myinvention, reference numeral 1 indicates a neon tube' light energized byan alternator 2 of a given frequency. 3 is an aeroplane having apropeller 4 through which the pilot views the neon tube beacon light 1.5 is a tachometer which registersthespeed of propeller 4.

In'Fig. 2, 6 is an ordinary neon light tube and 2 an alternator forenergizing tube 6.

The tube 6 might be one of several making up the neon tube beaconlight-1.

In Fig. '3 isillustrated another form of light frequency detectingmeans. In this figure 7 is a disc having a cut-out portion 8. The disc 7is'mounted on a suitable hearing and is driven from the engine shaft 11by 'means of a chain or other gearmg.

Fig. 4 represents another form of light tube which may be used forbeacon 1. ThlS tube.12 is of the same general rectifying type as isdisclosed in United StQtGSPELtQIlt No. 1,628,045, except that thedistance between the anodeand cathode of the tube is'made large so thatsufiicient light can be produced. Tube 12 comprises an envelope 13contalmng two electrodes 14 and 15 and a filling of rare gas at lowpressure. I The operation of the system shown 1n Flg. 1 is as follows:The pilot of aeroplane 3 upon seeing, a'beacon light such as 1, viewsthe light 1 through the revolving blades of propeller tthen varies thespeed of the engine driving propeller 4 until the propeller appears tostand stationary. When this illuwould be in synchronism with thefluctuations of light '1. The pilot would then read the tachometer andfrom the reading obtained would know the frequency of the lightfluctuations of beacon 1 and-by knowing the frequency would be able toidentify the beacon light. The beacon light I might be made of one orseveral tubes such as shown in Figs. 2 or 4, but would preferably bemade of one or more tubes such as shown in Fig. 4. With this type oftube the beacon would be shining only half of the time and hence thepropeller 4 would appear more clear cut. The arrangement shown in Fig. 3works in substantially the same manner as that shown in Fig. 1 exceptthat instead of utilizing the propeller 4 as a synchronizing means, theaeroplane pilot would view the light through opening 10 in a plate 9,which might be mounted on some part of the aeroplane in the line ofvision in the pilot. With this arrangement by properly regulating thespeed of the disc driving means the pilot would be enabled eitherentirely to occult the light from beacon 1 or allow it to shinecontinuously through the coinciding open- I tively.

ings 8 and 10 of disc 7 and plate 9 respec- The speed of the engine withthis arrangement would be determined by a tachometer in the same manneras shown in Fig.

' 1. The .disc 7 might be driven by means other than the aeroplaneengine, such .as an electric motor, for example. In such a case thetachometer would, of course, be connected to the disc so as to registerits speed.

Such an arran ement as I have disclosed would be particu arly usefulwhere several beacon lights for various landing fields were groupedtogether. Each light would be operated at a dilferent frequency known tothe pilot, and hence all. the pilot would have to do would be to'synchronize his indicator on I various lights successively. and thusdetermine the identity of the field he desired to use. L

The system might also be used on ships at sea and for other analogoususes.

It will be obvious tothose skilled in the art that the invention iscapable of a wide variety of modifications and adaptations and that thepresent disclosure is intended merely to illustrate its nature withoutlimiting its scope, which is definedin the appended claims.

0 What I claim is: 1. A vehicle guiding system comprising incombination, a vehicle, a light beacon, means whereby the brilliancy ofsaid light beacon 1s per1od1cally varied at a characteristic rate,

and stroboscopic, means on the vehicle for determining the periodicityof said variation, of brilliancy.

2. A vehicle guiding system comprising in combination, a vehicle, alight beacon; means for varying the brilliancy of said beacon at quencyand means inclu ing the aeroplane propeller for determining thefrequencyof variation of the candle ower of said light.

5. An aeroplane guiding system comprising in combination an aeroplane, aplurality of light beacons, means for periodically varying the candlepower ofeach of said beacons at a different characteristic frequency andstrobo scopic means on the aeroplane fordetermining the frequency ofvariation of the candle power of any one of said beacons.

6. An aeroplane guiding'system comprising in combination an aeroplane, alight beacon, means for varying the brilliancy of said beacon at a givenfrequency, means on the aeroplane for stroboscopically determining thefrequency of variation of said brilliancy and common means for ropellingthe aeroplane and actuating sai second mentioned means.

7. An aeroplane guiding system comprising a neon tube light beaconenergized by an alternating current source whereby the brilliancy ofsaid light is varied at a frequency in step with that of the alternatingcurrent and means on an aeroplane including the propeller thereof, fordetermining the frequency of saidalternating current.

8. An aeroplane guiding s stem comprising in combination an aerop ane, arectifying neon tube light beacon, alternating cur rent means ofcharacteristic frequency for energizing said neon tube, aropeller fordrivin the aeroplane throng which the light engine for turning saidpropeller, means for Y-varying thespeed of the engine and means forindicating the speed of' said engine,

from said beacon may be viewed, an

whereby the identity of said light beacon may be stroboscopicallydetermined.

9. In an object identifying system, a plurality of spaced objects,lights on some 0 said objects, means for varying the 'brilliancy of eachof said lights at a different characteristic frequency and meansonanother of said objects for stroboscopically determinirig saiddifferent frequencies. f

In testimony whereof, WILLIAM F. HEN DRY has signed his name to thisspecification this 26th day of April, 1927,.

' WILLIAM FJHENDRY.

